Like the photo comments say. Above the cabin.
Here is a photo from the boeing website:

Really never knew about this on a 77W. Looks like there's not much headroom in the rest area as it looks only half the height of the cabin. Guess they have to bow a bit when walking around or even crawl in the rest area, don't they?

It usually depends on the aircraft type. The 747 can be at the rear part of the aircraft and on the 777-200LR, it can be near the front. It all depends on the airline and their preferences. If you check the database on jetphotos, KLM has the same preference for the 747 and 777.

as i have mentioned in my previous post, the first cabin on most 777s have the same ceiling as with the rest of the aircraft: either "flat" without the overhead bins, or with the customary drop-down center bins.